I. Field of the application
The invention relates to the practice of cooling the rotary kiln shell, and more particularly, to an apparatus for the removal of heat from the cylinders of the rotary kiln recuperator cooler.
II. Description of the prior art
There is known in the art an apparatus for cooling the shell of a rotary kiln, which comprises a spiral of tubing arranged around the kiln shell with a space being formed therebetween; a coolant such as water circulates through said tubing. The tubes are fixed on support member. Mounted above the tubes are baffles.
Since carrier rings are not provided for in the apparatus construction, it is impossible to ensure strictly concentrical arrangement of the tubes. The misalignment of the tubes results in the impairment of the heat exchange between the kiln shell and the tubes.
In addition, such tube arrangement makes is impossible to conduct the inspection of the kiln shell during operation. Furthermore, the tube-mounting operation requires welding of an appreciable amount of separate half-turns of the tubes. The apparatus dismounting is likewise labour-consuming operation. Due to the absence of either housing or insulation above the baffles, the latter undergo abrupt cooling in the winter time and fail to reflect heat.
There is also known an apparatus for removing heat from the shell of the rotary kiln recuperator cooler, which comprises heat-exchange tubes intended for a coolant to circulate therethrough and fixed sectionwise on support members which concentrically encompass the kiln shell, the heat-exchange tubes being secured on the support members so as to encompass the kiln shell around its periphery with an annular space being formed between the tubes and the housing surface. To enhance the heat-removing efficiency, heat shields are arranged above each tube section or directly on the tubes.
The main disadvantage of the above-described apparatus if applied to the recuperator cooler, lies in its low cooling efficiency which is due to insufficiently developed heat-transfer area of the tubes. In addition, the apparatus of this type is complicated for maintenance and repair, the tube heat shields making the cooler inspection difficult.
It is an object of the invention to provide an apparatus for removing heat from cylinders of the rotary kiln recuperator cooler, which will permit the heat-transfer area thereof to be increased.
Another object of the invention is to provide an apparatus of the type permitting the mounting and servicing of the heat-exchange tubes to be substantially simplified.
These and other objects and features of the invention are attained in an apparatus for removing heat from cylinders of the rotary kiln recuperator cooler, comprising heat-exchange tubes intended for a coolant to circulate therethrough and fixed sectionwise on bow-shaped support members vertically arranged lengthwise of the cooler, according to the invention, the heat-exchange tubes are fixed on the lateral surfaces of the bow-shaped support members so as to go around the cooler surface along a wave line with a space of variable cross section being formed therebetween. Owing to such arrangement of the heat-exchange tubes, as well as due to the space formed between the surfaces of the cylinders and the heat-exchange tubes being of variable cross section, the heat-transfer area is substantially increased and, consequently, a greater amount of heat is removed from the cooler.
This is explained by the fact that the heat-transfer intensity is influenced by the surface area of the heat-exchange tubes rather than by the distance thereof from the surfaces of the cooler cylinders.
Moreover, with the space between the heat-exchange tubes and the surface of the cooler cylinders being of variable cross section, the apparatus servicing becomes easier.
It is preferable to mount on the heat-exchange tubes heat-removing elements rotatable about their axes, made of a high-temperature-resistant material and periodically brought into contact with the surfaces of the cooler cylinders.
This will intensify the rate of heat removal from the cooler effected by the heat-exchange tubes.